In many industries, it is desirable to view a path taken by a particular object, idea or signal, as it travels through for example, transportation, distribution, business or communication networks. Common examples include tracking of a courier package from an originating point to its destination, examining the travel of individuals through a transportation network, viewing a path a proposal may take within a business from conception through to final approval, or examining an assigned path of data traffic through a telecommunication network.
Such paths typically consist of nodes and links, with nodes representing hubs, intersections, action points, sources, destinations, etc., and links representing the logical or actual transportation or communication links between the nodes. For example, in a communication network, the nodes may be communication devices such as routers or antenna base stations, while the links may be any means of communication between two nodes such as through copper wire, optical cable, or microwaves. In a transportation network, nodes may be airports, train stations, or shipping ports, while the links may be air routes, train routes or shipping routes.
Many methods have been developed to view paths. One example is a geographic topology which displays nodes according to their geographic locations, as well as the links which connect the nodes. In one version, all nodes and all links are displayed, with the specific nodes and links comprising the path of interest highlighted in the geographic topology. In another version, only those nodes and links which make up the path of interest is displayed. Another example of a method of viewing paths is a logical topology, which is similar to the geographic topology except that the nodes are spatially arranged not according to their geographic locations, but in accordance with some other logical organization. A third example is a line view, wherein a path is represented by a simple linear representation of all of the nodes which comprise the path, with link representations therebetween.
Each of the above methods are useful for viewing simple paths. However, where paths become complex, these methods may fail. One source of complexity is the sheer number of nodes and links which may comprise a path. Another source of complexity is the amount of information which must be displayed in respect of each of the nodes and links to be viewed.
A third source of complexity is where the nodes are grouped into layers, wherein it may be desirable to know which nodes fall within which layer, and further, information respecting each layer may need to be viewed. One example of a network in which the nodes are grouped into layers is a distribution network, wherein the nodes may consist of source/destinations, storage facilities, trucking depots, and airports. In such a case, the nodes may be grouped into four distinct node layers, the first being a pick-up/delivery layer, the second being a storage layer, the third being a trucking layer, and the fourth being an air transportation layer. Thus a path from pick-up to delivery may progress from nodes in the pick-up/delivery layer, to the trucking layer, to the air transportation layer, to the storage layer, to the trucking layer, and back to the pick-up/delivery layer. Similarly, in a telecommunication network, node layers may include an IP (Internet Protocol) layer, a SONET (Synchronous Optical Network) layer, an SDH (Synchronous Digital Hierarchy) layer, an ATM (Asynchronous Transfer Mode) layer, and an optical layer. In a business plan network, node layers may include a planning committee layer, a finance layer, an engineering layer, and a marketing layer. Of course, there may exist sub-layers within each layer. For example, in the telecommunication context, there may be multiple SONET layers, grouped by geographic location, for example.
Where nodes are grouped into layers, it may at times be desirable to view all nodes in the path, grouped according to the layer in which a particular node may belong. Other times, it may be desirable to omit nodes of a certain layer, allowing an individual to view only those layers of interest. Current solutions include identifying in a geographic or logical topology, or in a linear representation, nodes which belong in a particular layer using a distinctive colour, special icons, text, or by drawing a box around nodes comprising a node layer. However, such identifiers tend to clutter the path representation, and make it difficult to discern the node layers. Further, such solutions fail when a large number of nodes need to be viewed.